“This is part of the overall national campaign to free Justina,” said the Rev. Patrick Mahoney, a family spokesman and head of the Washington-based Christian Defense Coalition, which organized the event. “When Justina is returned back to her family, we want her to know that there were scores standing with her who believed in this cause and came out to stand in solidarity with her.”

The case drew widespread attention after the Globe reported in December that the state took custody of Pelletier at the behest of Boston Children’s Hospital, which then kept her in a locked psychiatric ward for nearly a year. Doctors at Children’s thought Pelletier’s medical problems were largely psychiatric and not the result of mitochondrial disorder, an earlier working diagnosis made by doctors at Tufts Medical Center and supported by Pelletier’s parents.

The state Department of Children and Families, under pressure following a series of high-profile scandals, indicated Friday it was now trying to return Pelletier to Connecticut and allow her future medical care to be overseen by Tufts Medical Center.

Participants in the rally, some of whom drove hours from nearby states to attend, held signs reading, “FREE JUSTINA,” and cheered Mahoney as he gave an animated interview to television reporters.

David and Stephanie Meader of Plaistow, N.H. said Pelletier’s case resonated with them because they care for an immediate family member with a complicated mental illness.

“At times, there were differing opinions about his diagnosis,” David Meader said. “We’re realizing now that we were very vulnerable, and had there been a fight, we could have lost [custody of] him in a heartbeat.”

The Meaders said it was “unimaginable” that parents who had not withheld care from their child could lose custody, and they urged Pelletier’s parents to continue their public fight.

Kimberly Gower-Hall, 47, of Sudbury, said she also had a medically fragile child, and came to the rally with a message for the Pelletiers.

“I know what it’s like to endure this,” she said. “They need to keep reaching out to people who can help emotionally and medically. They’re going to need healing on many different levels.”

Pelletier’s parents did not attend Saturday’s rally because they were emotionally exhausted, Mahoney said, adding that the family is facing a financial crisis because of Pelletier’s medical bills.

Event organizers said they intentionally kept out of view of the Wayside Youth and Family Support Network building to avoid disturbing patients or staff there.

The care center issued a statement saying it is not involved in custody decisions, and that privacy rules prevented it from confirming any information about patients there. But a person familiar with operations and staff at the nonprofit, and who asked not to be named because of the sensitivity of the case, said the rally was an “unwelcome distraction” for caregivers trying to focus on treating their young clients.

State Representatives Marc Lombardo and Jim Lyons, both Republicans, also spoke at the rally, slamming DCF and calling for Pelletier to be transferred back to her parents’ custody.

Conservative and religious advocacy groups have latched onto aspects of the case, with some calling it emblematic of the problems that arise when government intervenes in family and medical decisions.

Mahoney, a veteran activist who made headlines during the Terri Schiavo controversy in Florida, insisted Pelletier was not a prop in a broader ideological campaign, saying the purpose of Saturday’s rally was simply to pray for her and others with similar cases.

But, he called the image of Pelletier in a wheelchair a “compelling visual.”

“There’s a growing concern about government encroachment on the health care issue,” he said. “Justina’s case is the canary in the coal mine of a broader problem nationwide of the erosion of parental rights.”